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The universe appears to be finely calibrated to support the existence of intelligent life and promote scientific discovery. To understand what I mean, imagine you found yourself in a strange house. To your astonishment, you discover that parts of the house resonate with perfect musical pitch when struck or bumped into. There are rooms where you can play chords by hitting several things at once, or perform a scale by tapping along the kitchen tile. You might suspect the house was designed for musical inhabitants. Suppose further that the feng shui of the house naturally leads people through its rooms in a way that creates a unique, captivating melody, when done right. You might additionally suspect the designer of the house intended its inhabitants to discover this hidden melody. As cheesy and flawed as this analogy might be, the musical house is similar in many ways to our universe.

A 'Tailor-Made' Universe

Just as the imaginary house was finely "tuned" to support musical inhabitants, our universe appears to be fine-tuned to support intelligent inhabitants like ourselves. If certain aspects of our universe — certain laws, physical constants, and initial conditions — were much different than they are, we very likely wouldn't, and couldn't exist. Some examples include:

The strength of gravity

The strength and range of the strong nuclear force (holds protons and neutrons together in the nucleus of an atom — protons would otherwise repel each other)

The strength of the electromagnetic force (holds electrons in orbit around atomic nuclei and governs all chemical interactions)

The value of the cosmological constant (believed to drive the inflation and accelerated expansion of the universe)

a change of as little as 0.5 percent in the strength of the strong nuclear force, or 4 percent in the electric force, would destroy either nearly all carbon or all oxygen in every star, and hence the possibility of life as we know it. Change those rules of our universe just a bit, and the conditions for our existence disappear![1]

This is why he concludes,

The laws of nature form a system that is extremely fine-tuned, and very little in physical law can be altered without destroying the possibility of the development of life as we know it. Were it not for a series of startling coincidences in the precise details of physical law, it seems, humans and similar life-forms would never have come into being.[2]

Not only do these laws, constants, and conditions need to be finely tuned individually (like individual strings on a guitar), they must also be fine-tuned in relation to each other! Just like you can't play music on an out-of-tune instrument, our universe couldn't support life if it wasn't similarly fine-tuned. This surprising coincidence of a finely tuned universe surely calls for explanation. Stephen Hawking agrees, he says, "Our universe and its laws appear to have a design that both is tailor-made to support us and, if we are to exist, leaves little room for alteration. That is not easily explained, and raises the natural question of why it is that way."[3]

When you look at the probabilities physicists have calculated for the odds of a fine-tuned universe like ours happening by chance, it pushes one to consider other explanations....like God, for example. It's not just people that already believe in God who acknowledge this. The late Christopher Hitchens admitted that the fine-tuning of the universe was the best argument for God he'd come up against, and said all his atheist comrades felt the same. Likewise, Hawking acknowledges that, "the extreme fine-tuning of so many of the laws of nature could lead at least some of us back to the old idea that this grand design is the work of some grand designer,"[4] even though he disagrees with that conclusion.

But the fine-tuning gets even better.

Designed for Discovery

There appears to be an eerie correlation between the finely tuned conditions necessary for intelligent life to exist and the best conditions for making scientific discoveries. Similar to how the arrangement of the musical house lead inhabitants to discover its hidden melody, the arrangement of our universe — the cosmic feng shui, if you will — has lead humans to discover all kinds of hidden truths through science. For example:

The tiny region of the electromagnetic spectrum that gives life to most organisms on Earth — namely, light — also happens to be the same tiny region that the human eye is sensitive to. Without light, we could not see anything, and thus could not observe the world.

The extraordinarily rare conditions that make Earth's atmosphere able to support life also happen to be the same rare conditions that make the atmosphere transparent, giving humans a clear view into the night sky and the universe beyond.

The highly improbable, celestial conditions that make our Earth habitable — having a large enough moon to affect oceanic tides, a right sized star the perfect distance away, etc. — also happen to be the same conditions that make perfect solar eclipses possible (something that only happens on Earth, by the way). Scientists have made a number of fortuitous discoveries while observing solar eclipses — discoveries that have opened doors of understanding into the composition of stars and galaxies. Scientists likely would not have made these discoveries without perfect solar eclipses, since that is the only time the Sun's corona is visible. So the only place where perfect solar eclipses occur, also happens to be the only place where there are people to observe them and learn from them.

The mathematical structure of the universe (finely tuned) makes intelligent life possible. It also enables us humans — creatures that just happen to have mathematical intelligence — to make theoretical predictions and discover things about the universe that we couldn't otherwise.

I could go on, but I don't need to. You get the picture. Because the universe is so finely tuned to support life, it is reasonable to believe that the entity that brought the universe into being, that is the explanation for why it exists, and that is the source of its law-like order, is also the entity that designed it to be habitable. Moreover, in light of the strange correlation between the conditions for habitability and scientific discovery, it's reasonable to believe this same entity wants us, even beckons us to "search things out," to explore and discover the hidden depths of nature's beauty. And, unsurprisingly, it appears music is also part of that beckoning. Perhaps my house analogy isn't too far off after all. Thus, we arrive at a personal and intelligent designer of the universe.

The argument:

The fine-tuning of the universe is due to either physical necessity, chance, or design.

It is highly improbable that it is due to chance or physical necessity.

Therefore, the fine-tuning of the universe is most likely due to design.

There are only two possibilities here: (1) either God exists or (2) he doesn't. If atheism were true, it would be improbable in the extreme for a single, finely tuned universe to exist. Given this improbability, our observation that the universe is fine-tuned supports the hypothesis that God exists much more strongly than the hypothesis that he doesn't. Thus, the fine-tuning of the universe is a good reason to believe God exists.

Common Objections:

1. Our universe is just one of an infinite number of universes. Given an infinite number of chances, a highly improbable universe like ours is guaranteed to eventually occur. Even if it were true that our universe is part of a larger multiverse (an idea that is only a theoretical speculation at this point), there could not be an infinite number of universes currently in existence, for a couple of reasons:

(1) Recall that Alexander Vilenkin proved our best models of the universe are not past-eternal. There had to be a beginning at some point, whether we're talking about a single universe or a larger multiverse. That would mean there has only been a finite amount of time for multiple universes to develop. In other words, if there are other universes, there is only a finite number of them. So, it is not guaranteed that a universe like ours would eventually form. In fact, the odds of our universe forming by chance are so incomprehensibly low, positing a multiverse may not even put a dent in the extreme improbability of it. For example, even if there were currently as many universes in existence as there are approximate atoms in the entire observable universe (a number estimated to be 10^80 — that's a 1 with 80 zeros behind it), that is still not enough chances to guarantee even one of the finely tuned conditions! The cosmological constant alone is estimated to be finely tuned to 1 in 10^120 (that's a 1 with 120 zeros behind it!).[5]

(2) Apart from Vilenkin's theorem for the finitude of the past, there are other independent reasons to believe that an infinite set of actually existing universes is impossible. Recall the Kalām argument and astrophysics paper referred to in my first post. Both show that the actual existence of an infinite number of things leads to philosophical and mathematical contradictions and absurdities. That should give us further confidence that if alternate universes exist, there can't be an infinite number of them. Furthermore, philosopher Robin Collins has argued that the multiverse mechanism which supposedly creates these alternate universes — the "universe-making machine" — itself has to be finely tuned![6] Thus, the multiverse objection is practically useless for explaining how our universe could be so extremely fine-tuned. At best, it only moves the problem back one step.

2. The universe is finely tuned because of physical necessity. Given the laws of nature, the universe had to be this way. A few things: (1) even if that were the case, it doesn't explain why the laws of naturethemselves are finely tuned — they certainly didn't have to be this way; (2) actually a number of the constants and initial conditions are not determined by any law of nature that we know of, they seem arbitrary — one example is the apparent unequal distribution of matter vs. antimatter in the universe; (3) this objection amounts to the claim that it is physically impossible for the universe to be uninhabitable. That's a pretty strong assertion that needs an argument to back it up.

3. We shouldn't be surprised that the universe is habitable. If it wasn't, we wouldn't be here. Um, yeah, that's correct. But you're merely stating a truism — like saying, "Survivors are here because they survived." That doesn't explain anything. It is not the fact that the universe is habitable that is surprising. It is the fact that so many coincidences had to occur with such mind-blowing precision for the universe to be habitable that is surprising. Such a rare situation calls for an explanation, not a truism.

4. It doesn't matter how improbable it is — somebody has to win the lottery, right? We just happen to be the lucky winners! In a state lottery, yes, by sheer odds someone is bound to eventually win. But that's only because the number of possible lottery ticket combinations is proportional to the number of people playing. For example, the odds of winning the jackpot in the U.S. Powerball lottery is 1 in 175,223,510. But tickets are sold in 44 different U.S. states/jurisdictions. That's a lot of people. So, someone is bound to eventually win. But we have no reason to think the odds of the cosmos are like that. If our universe is all there is, then it would be more like one person buying a single ticket for every lottery game in the U.S., and winning all of them simultaneously....1,000 times in a row! If that happened even once, no one in their right mind would accept the explanation, "Someone had to win, right?" Rather, they would naturally suspect some conspiracy going on. The only way the "somebody has to win" objection could be acceptable is if there were an actual infinite number of universes currently in existence; but that's likely not the case (see my explanation above).

Further Reading:

*To better understand the goals and limits of this blog series, please read the Introduction, if you haven't already. Thanks!